Association between CYP17 gene polymorphism and risk of breast cancer in young women

Long-term exposure to oestrogens is a well-recognised risk factor for breas t cancer, whereas little is known about the influence of polymorphisms of g enes involved in oestrogen biosynthesis and metabolism. A candidate, contai ning a single bp polymorphism, T-->C, (designated, A2 allele), might be the CYP17 gene, which codes for an enzyme involved in oestrogen synthesis. Thi s polymorphism creates an additional Spl-type promoter site (CCACC box), wh ich has been shown to be associated with increased serum oestrogen levels. We performed a case control study, to evaluate association of the CYP17 gen e polymorphism with risk of breast cancer in young women (younger than 37 y ears). We found a statistically significant increased risk in carriers of a t least I A2 allele [odds ratio (OR), 2.0; 95% confidence interval (CI), 1. 1-3.5, p = 0.027], and a trend toward a gene-dose effect illustrated by a s lightly higher risk for A2-homozygous subjects (OR, 2.8) than for heterozyg ous women (OR, 1.9). Furthermore, when we investigated the CYP17 genotype i n relation to tumour characteristics, breast cancer patients with I or 2 A2 alleles tended to have lower oestrogen receptor levels (risk ratio, 0.70; CI, 0.41-1.2, p = 0.44). Our findings suggest that CYP17 gene polymorphism influences breast carcinogenesis in young women. Int. J. Cancer (Pred. Onco l.) 84:350-353, 1999. (C) 1999 Wiley-Liss, Inc.